1. Field of the Invention
The present invention relates to an apparatus for automatically replacing tools. More specifically, the present invention relates to the structure of an automatic tool-replacement arm used in the so-called machining center.
2. Description of the Related Art
In recent years, the so-called machining center has often been used to automatically and efficiently carry out machining work such as cutting or grinding. The machining center is adapted to select a suitable machining tool in accordance with the type of the necessary machining work, and automatically mount the selected tool onto the spindle on the main body of the relevant machine tool, so that machining work is performed using the tool. An automatic tool-replacement arm and other mechanisms are provided to mount and dismount tools.
The machining work may be performed in various conditions in the machining center. For instance, the number of the machining tool mounted on the main body thereof may not necessarily be one; in some cases, a single machining tool may be mounted, whereas in other cases, a plurality of machining tools may be juxtaposed so that they will perform machining operations simultaneously. Furthermore, a nozzle for supplying a coolant to each machining tool may also be disposed.
An arm serving as the conventional automatic tool-replacement mechanism is mainly capable of the following functions: holding one particular tool to mount it on or dismount it from the main body of the machine tool; returning the dismounted tool to a magazine positioned adjacent to the main body of the machine tool; and holding a new tool to mount it on the main body of the machine tool.
Therefore, when a plurality of tools are mounted on the main body of the machine tool, the following problem may arise. If some or all of the plurality of tools have to be, for instance, replaced, the replacement work cannot be completed at one time, more specifically, by one travel of the automatic tool-replacement arm. Thus, replacement work requires a long time. In order to complete the replacement work within a short time, a plurality of automatic tool-replacement arms might be provided. This, however, may lead to inevitable increase in the size of the entire apparatus.